A method of recovering information encoded by a modulated sinusoidal waveform having first, second, third and fourth data notches at respective phase angles, where a power of the modulated sinusoidal waveform is reduced relative to a power of an unmodulated sinusoidal waveform within selected ones of the first, second, third and fourth data notches so as to encode input digital data. The method includes receiving the modulated sinusoidal waveform and generating digital values representing the modulated sinusoidal waveform. A digital representation of the unmodulated sinusoidal waveform is subtracted from the digital values in order to generate a received digital data sequence, which includes digital data notch values representative of the amplitude of the modulated sinusoidal waveform within the first, second, third and fourth data notches. The input digital data is then estimated based upon the digital data notch values.

A method by which a base station transmits a reference signal in a wireless communication system can comprise the steps of: transmitting, to a terminal, information on a modulation method of a reference signal for estimating a phase difference between symbols in a time domain; and transmitting, to the terminal, the reference signal, for estimating the phase difference between the symbols, to which the modulation method is applied.

A method of recovering information encoded by a modulated sinusoidal waveform having first, second, third and fourth data notches at respective phase angles, where a power of the modulated sinusoidal waveform is reduced relative to a power of an unmodulated sinusoidal waveform within selected ones of the first, second, third and fourth data notches so as to encode input digital data. The method includes receiving the modulated sinusoidal waveform and generating digital values representing the modulated sinusoidal waveform. A digital representation of the unmodulated sinusoidal waveform is subtracted from the digital values in order to generate a received digital data sequence, which includes digital data notch values representative of the amplitude of the modulated sinusoidal waveform within the first, second, third and fourth data notches. The input digital data is then estimated based upon the digital data notch values.

A system and method for narrowband sinewave modulation. The system includes an input buffer for storing input digital data and a sub-periodic modulator for encoding the input digital data in a periodic waveform. The sub-periodic modulator encodes one or more bit values of the input digital data within each period of the periodic waveform. One or more digital-to-analog converters generate an encoded analog waveform from a digital representation of the periodic waveform wherein the encoded analog waveform is of a frequency f and a power P. The encoding is performed by the sub-periodic modulator such that any signal of frequency f resulting from the encoding is of a power P at least 50 dB less than power P, where f is offset from f by more than 25 Hz.

A data communications system and method having high spectral efficiency. The method includes encoding input digital data using a plurality of symbol waveforms. Each symbol waveform occupies a period of a composite encoded waveform and represents one or more bits of the input digital data. Each symbol waveform has a first elliptical segment and a second elliptical segment of opposite polarity. The encoding includes defining each symbol waveform so that (i) a zero crossing from the first elliptical segment to the second elliptical segment of the symbol waveform is different for each of the symbol waveforms, and (ii) an energy of the first elliptical segment of the symbol waveform is substantially equal to an energy of the second elliptical segment of the symbol waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the composite encoded waveform.

A system and method for encoding multi-bit features into sinusoidal waveforms at selected phase angles. The method includes receiving input digital data and encoding the input digital data in a sinusoidal waveform by modulating the sinusoidal waveform at selected phase angles within a period of the sinusoidal waveform, thereby creating a modulated sinusoidal waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the modulated sinusoidal waveform. The modulating includes forming a first data notch at a first phase angle of the selected phase angles wherein the first data notch includes a first plurality of transition features and subtends a first phase angle range about the first phase angle, the first plurality of transition features being representative of a first plurality of bit values included within the input digital data.

A system and method for waveform modulation includes encoding input digital data at selected phase angles of an unmodulated sinusoidal waveform. The encoding includes selectively reducing a power of the unmodulated sinusoidal waveform at the selected phase angles in accordance with bit values of the input digital data so as to respectively define first, second, third and fourth data notches in the modulated sinusoidal waveform. An encoded analog waveform is then generated from a digital representation of the modulated sinusoidal waveform. The encoding is performed so that energies associated with the first and third data notches are balanced and energies associated with second and fourth data notches are also balanced. Each of the energies corresponds to a cumulative power difference between a power of the unmodulated sinusoidal waveform and a power of the modulated sinusoidal waveform over a phase angle range subtended by one of the data notches.

A multi-carrier data communications system and method having high spectral efficiency. The method includes encoding input digital data at selected phase angles of a plurality of sinusoidal waveforms to create a plurality of modulated sinusoidal waveforms. An output analog waveform is generated where the output analog waveform includes a plurality of encoded analog communication signals corresponding to a plurality of digital representations of the plurality of modulated sinusoidal waveforms. The encoding is performed so that adjacent ones of the plurality of modulated sinusoidal waveforms are separated in frequency by less than 15 Hz and any sideband included within the output analog waveform is of a power at least 50 dB below a power of the encoded analog communication signal associated with the sideband.

Phase noise is corrected in a communication system including a modulated signal having a constellation including multiple constellation points. The system and methods include a coarse phase recovery followed by a fine phase recovery. Coarse phase corrected points can be generated using an M.sup.th power operation. Fine phase corrected points can be generated by rotating each coarse phase corrected point by an angle that is determined by the location of that coarse phase corrected point in the constellation, and applying a phase offset function to each transformed point. A phase noise mitigated constellation can be generated by derotating the fine phase corrected points.

The present disclosure may provide a device and method for independent phase adjustment of a PAM receiver. The device includes: a plurality of samplers configured to perform sampling for signal level decision of multi-level input data; a global clock source configured to provide a common sampling clock to the samplers; and a plurality of phase adjusters configured to respectively adjust a phase of the common sampling clock to provide a sampling phase applied to a corresponding sampler. According to the present disclosure, it is possible to achieve reliable BER performance by independently adjusting a sampling phase of a sampler corresponding to each eye opening even in the presence of unsymmetric eye openings.